Keyboards are generally used to input various commands to electronic apparatuses and machines. In this description, the term “keyboard command” is intended to represent all possible types of input that can be made by means of a keyboard, keypad, remote control, control panel or the like for electronic apparatuses and machines, e.g. computers, telephones, TV sets, sound systems, medical equipment, engineering machines, instruments, etc.
Typically, such keyboard commands are input, e.g., for writing or controlling computer programs and applications, by the user pressing keys or buttons with his/her fingers, which however in some situations is not possible or desirable. Hence, there is a need to enable keyboard commands without requiring the use of hands, e.g. for disabled persons or when both hands are busy with other activities such as when driving a car and when operating various machines and instruments. For example, a doctor, dentist or nurse may need to input data to a computer during examination or treatment of a patient requiring work with the hands.
Previously, different solutions have been proposed where the user can control a computer cursor by means of movements of the tongue and/or other parts of the mouth cavity or the face. The previously known solutions of the above typically involve some actuator corresponding to the mouse, which is positioned inside the mouth cavity, e.g. a ball or the like applied at a row of teeth or in the palate, see e.g. DE 195 12 595 A1. However, it may be perceived as a nuisance for the user to have a foreign object in the mouth, particularly in terms of hygienics. It is also necessary to position the actuator properly in the mouth cavity, as well as cleaning and maintaining it, resulting in additional efforts.
WO 02/075515 discloses a solution for controlling a cursor on a computer screen by registering ultrasonic signals that are reflected against the user's tongue and/or mouth cavity, which does not require any device inside the mouth.
There are also solutions for disabled persons based on registration of eye movements. However, this technique is relatively expensive and difficult to realize with sufficient accuracy, further requiring a lot of training of the user. Moreover, the user is not able then to focus his/her eyes on other things.
However, none of the above-mentioned solutions is particularly suitable for relatively easy and swift input of a range of different specific keyboard commands, including e.g. numerals, letters and other characters.